There are several factors influencing the rate of a chemical reaction. It is essential to understand and to be able to predict the conditions affecting the reaction rate.
A catalyst is a substance which alters the rate of a chemical reaction staying chemically unchanged at the end of the process. Catalysts increase the rate of a chemical reaction by lowering the reaction activation energy and reaching the equilibrium faster.
Hydrogen peroxide, dishwashing liquid, and methylene blue or any other dye are stirred with a rod. Potassium iodide is added at once to that solution. Colored foam forms rising quickly up the cylinder and erupting out, like toothpaste squirted out of a tube.
Wear safety goggles when doing this experiment, since the foam shoots very high out of the cylinder and could go towards your face. Do not stand over the graduated cylinder because the product forms quickly and the reaction is exothermic.
This experiment shows the decomposition of hydrogen peroxide catalyzed by potassium iodide. Hydrogen peroxide (H2O2) decomposes into water and oxygen gas, but normally the reaction is to slow to be easily perceived or measured:
Iodide ion from potassium iodide acts as a catalyst – it speeds up the reaction without being consumed in the reaction process. The iodide ion changes the mechanism, by which the reaction occurs:
Oxygen quickly leaves the system causing strong foaming of the detergent, so the foam erupts out. Steam rising from the foam shows that the reaction is exothermic (gives off heat). Minimum quantities of iodine are being liberated and can be detected by its color if the experiment is done without dyes.